US20220149592A1 - Optical semiconductor module - Google Patents
Optical semiconductor module Download PDFInfo
- Publication number
- US20220149592A1 US20220149592A1 US17/521,660 US202117521660A US2022149592A1 US 20220149592 A1 US20220149592 A1 US 20220149592A1 US 202117521660 A US202117521660 A US 202117521660A US 2022149592 A1 US2022149592 A1 US 2022149592A1
- Authority
- US
- United States
- Prior art keywords
- wire
- semiconductor module
- optical semiconductor
- inductor
- transmission line
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Images
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/02—Structural details or components not essential to laser action
- H01S5/022—Mountings; Housings
- H01S5/023—Mount members, e.g. sub-mount members
- H01S5/02315—Support members, e.g. bases or carriers
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/02—Structural details or components not essential to laser action
- H01S5/024—Arrangements for thermal management
- H01S5/02407—Active cooling, e.g. the laser temperature is controlled by a thermo-electric cooler or water cooling
- H01S5/02415—Active cooling, e.g. the laser temperature is controlled by a thermo-electric cooler or water cooling by using a thermo-electric cooler [TEC], e.g. Peltier element
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/02—Structural details or components not essential to laser action
- H01S5/022—Mountings; Housings
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/02—Structural details or components not essential to laser action
- H01S5/022—Mountings; Housings
- H01S5/023—Mount members, e.g. sub-mount members
- H01S5/0232—Lead-frames
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/02—Structural details or components not essential to laser action
- H01S5/022—Mountings; Housings
- H01S5/0233—Mounting configuration of laser chips
- H01S5/02345—Wire-bonding
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/02—Structural details or components not essential to laser action
- H01S5/026—Monolithically integrated components, e.g. waveguides, monitoring photo-detectors, drivers
- H01S5/0261—Non-optical elements, e.g. laser driver components, heaters
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/04—Processes or apparatus for excitation, e.g. pumping, e.g. by electron beams
- H01S5/042—Electrical excitation ; Circuits therefor
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/06—Arrangements for controlling the laser output parameters, e.g. by operating on the active medium
- H01S5/062—Arrangements for controlling the laser output parameters, e.g. by operating on the active medium by varying the potential of the electrodes
- H01S5/06226—Modulation at ultra-high frequencies
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/02—Structural details or components not essential to laser action
- H01S5/022—Mountings; Housings
- H01S5/0239—Combinations of electrical or optical elements
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/02—Structural details or components not essential to laser action
- H01S5/024—Arrangements for thermal management
- H01S5/02476—Heat spreaders, i.e. improving heat flow between laser chip and heat dissipating elements
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/02—Structural details or components not essential to laser action
- H01S5/026—Monolithically integrated components, e.g. waveguides, monitoring photo-detectors, drivers
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/02—Structural details or components not essential to laser action
- H01S5/026—Monolithically integrated components, e.g. waveguides, monitoring photo-detectors, drivers
- H01S5/0265—Intensity modulators
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/06—Arrangements for controlling the laser output parameters, e.g. by operating on the active medium
- H01S5/068—Stabilisation of laser output parameters
Definitions
- the present disclosure relates to an optical semiconductor module.
- Japanese Unexamined Patent Publication No. 2017-107920 discloses a semiconductor module having a laser unit and an optical modulator unit manufactured on a substrate.
- the semiconductor module includes a semiconductor laser in which a DFB laser and an EA modulator are integrated and a subcarrier having a high-frequency wiring which is a coplanar wiring.
- the semiconductor laser has a ground electrode on a back surface.
- a step difference formed with an upper stage and a lower stage is formed on an upper surface of the subcarrier.
- a lower surface of the subcarrier is flat.
- the high-frequency wiring has a coplanar line formed on the upper stage of the upper surface of the subcarrier.
- the coplanar line includes a ground wiring and a signal wiring.
- the ground electrode is formed in the lower stage of the upper surface of the subcarrier.
- the semiconductor laser is disposed so that the ground electrode provided on the back surface is in contact with the ground electrode of the subcarrier.
- An optical semiconductor module includes a board including a transmission line; a block including a low-permittivity material; an inductor mounted on the block, the inductor being connected with the transmission line via a first wire, the first wire having a first inductance; a semiconductor laser device mounted on the board, the semiconductor laser device being connected with the transmission line via a second wire, the second wire having a second inductance smaller than the first inductance; and a housing configured to accommodate the board, the block, the inductor, and the semiconductor laser device.
- An optical semiconductor module includes a board; a block including a low-permittivity material and a transmission line; an inductor mounted on the block, the inductor being connected with the transmission line via a first wire, the first wire having a first inductance; a semiconductor laser device mounted on the board, the semiconductor laser device being connected with the transmission line via a second wire, the second wire having a second inductance smaller than the first inductance; and a housing configured to accommodate the board, the block, the inductor, and the semiconductor laser device.
- FIG. 1 is a plan view schematically illustrating an internal structure of an optical semiconductor module according to an embodiment.
- FIG. 2 is a plan view schematically illustrating a substrate on which a semiconductor laser element is mounted and a block on which an inductor is mounted in the optical semiconductor module.
- FIG. 3 is a side view schematically illustrating the inductor mounted on the block.
- FIG. 4 is a plan view schematically illustrating the substrate on which the semiconductor laser element is mounted and the block on which the inductor is mounted in an optical semiconductor module different from that in FIG. 2 .
- FIG. 5 is a diagram illustrating an equivalent circuit of an exemplary optical semiconductor module.
- FIG. 6 is a diagram illustrating an equivalent circuit which is a simplification of the equivalent circuit of FIG. 5 .
- FIG. 7 is a diagram illustrating an equivalent circuit of an optical semiconductor module according to a reference example.
- FIG. 8 is a graph illustrating an example of a relationship between frequency and transmission characteristics.
- FIG. 9 is a graph illustrating an example of a relationship between frequency and transmission characteristics.
- FIG. 10 is a diagram illustrating an equivalent circuit of an optical semiconductor module according to a modified example.
- FIG. 11 is a side view schematically illustrating a temperature control element, a substrate, and a semiconductor laser element of the optical semiconductor module of FIG. 2 .
- FIG. 1 is a plan view schematically illustrating an internal structure of an optical semiconductor module 1 according to a first embodiment.
- the optical semiconductor module 1 includes, for example, a rectangular housing 2 and external terminals 3 provided at one end of the housing 2 in a direction D 1 which is the longitudinal direction of the housing 2 .
- the external terminals 3 are aligned at one end of the housing 2 in the direction D 1 along a direction D 2 which is the width direction of the housing 2 .
- the direction D 2 is a direction intersecting the direction D 1 .
- the external terminals 3 are, for example, a terminal that receives a high-speed electric signal from the outside, a terminal that receives a drive current of a laser diode, a terminal that receives a drive current of a TEC, a monitor terminal for detecting a temperature of the laser diode, a terminal that supplies a ground potential (reference potential), and the like.
- As signals exchanged with the outside via the external terminals 3 there are high-speed signals and low-speed signals.
- the low speed signal includes a DC signal.
- the housing 2 has an inner wall 2 b that defines an internal space S of the housing 2 .
- An optical output unit 4 that outputs a light beam L (optical transmission signal) is provided at an end of the housing 2 opposite to the external terminal 3 in the direction D 1 .
- the optical semiconductor module 1 includes, for example, a transmission line 5 , a pad 6 which is a DC pad, and a thermo-electric cooler (TEC) 7 which is a temperature control element in the internal space S of the housing 2 .
- FIG. 2 is a schematic plan view in which an upper structure of the TEC 7 is enlarged.
- FIG. 11 is a side view schematically illustrating the upper structure of the TEC 7 .
- the optical semiconductor module 1 includes the TEC 7 , an AlN (Aluminum Nitride) substrate 8 (board) on which a semiconductor laser element 10 is mounted, and a block 9 on which an inductor 15 is mounted.
- the transmission line 5 and the pads 6 are formed on the inner surface of the housing 2 .
- the transmission line 5 and the pads 6 are connected to the external terminals 3 by the wiring penetrating the inner wall 2 b .
- the wirings connecting each of the transmission line 5 and the pad 6 to the external terminal 3 is formed by, for example, metal plating or thin film deposition.
- the transmission line 5 includes a signal wiring 5 s extending in one direction at a certain distance from a ground wiring 5 g running in parallel.
- the AlN substrate 8 is stacked and mounted on the TEC 7 in a direction D 3 which is the height direction.
- the direction D 3 is a direction intersecting direction D 1 and direction D 2 .
- the housing 2 accommodates, for example, the TEC 7 , the AlN substrate 8 , the block 9 , the semiconductor laser element 10 , and the inductor 15 in the internal space S.
- the TEC 7 has a heat sink surface 7 a and a temperature control surface 7 b .
- the TEC 7 is mounted on the housing 2 with the heat sink surface 7 a in contact with the housing 2 .
- the temperature control surface 7 b is located opposite to the heat sink surface 7 a in the direction D 3 .
- the heat sink surface 7 a and the temperature control surface 7 b are planes parallel to the directions D 1 and D 2 .
- the AlN substrate 8 is mounted on the temperature control surface 7 b in contact with the temperature control surface 7 b .
- the AlN substrate 8 has a first surface 8 a which is a lower surface and a second surface 8 b which is an upper surface.
- the first surface 8 a is in surface contact with the temperature control surface 7 b .
- the second surface 8 b is a reverse surface of the first surface 8 a .
- the AlN substrate 8 has the second surface 8 b opposite to the TEC 7 .
- the semiconductor laser element 10 is mounted on the second surface 8 b .
- the block 9 is juxtaposed with the AlN substrate 8 on the TEC 7 .
- the TEC 7 performs the temperature controlling of, for example, the semiconductor laser element 10 .
- heat is absorbed in the temperature control surface 7 b , and the heat amount absorbed is exhausted from the heat sink surface 7 a .
- the semiconductor laser element 10 is cooled via the AlN substrate 8 .
- heat is allowed to flow through the TEC 7 in a direction opposite to the predetermined current, heat is absorbed on the heat sink surface 7 a , and the heat amount absorbed is exhausted from the temperature control surface 7 b .
- the semiconductor laser element 10 is heated via the AlN substrate 8 .
- the block 9 is made of a low dielectric constant material (low-permittivity material).
- the block 9 is made of quartz.
- a relative permittivity of the low dielectric constant material is 3 to 5.
- the AlN substrate 8 includes, for example, an insulator.
- the relative permittivity of the low dielectric constant material of the block 9 is smaller than the relative permittivity of the insulator of the AlN substrate 8 .
- the relative permittivity of the insulator is 8 to 10.
- the semiconductor laser element 10 is, for example, an Electro-absorption Modulator integrated Laser (EML).
- EML Electro-absorption Modulator integrated Laser
- the semiconductor laser element 10 includes a laser diode 10 b and an optical modulator 10 c (modulator).
- the optical characteristics and the electrical characteristics of the semiconductor laser element 10 can be stabilized against changes in the external environmental temperature.
- the peak wavelength of the optical signal output from the semiconductor laser element 10 can be maintained within a predetermined range.
- FIG. 3 is a side view schematically illustrating the block 9 and the inductor 15 .
- the block 9 has a third surface 9 a which is a lower surface and a fourth surface 9 b which is an upper surface.
- the third surface 9 a is connected to the temperature control surface 7 b .
- the fourth surface 9 b is a surface opposite to the third surface 9 a .
- the fourth surface 9 b faces the inductor 15 .
- a wiring 9 c is formed on the fourth surface 9 b .
- the block 9 is mounted, for example, on the temperature control surface 7 b of the TEC 7 .
- the third surface 9 a of the block 9 is in contact with, for example, the temperature control surface 7 b of the TEC 7 .
- the TEC 7 is mounted on the inner surface of the housing 2 with the heat sink surface 7 a in contact with the inner surface of the housing 2 .
- the fourth surface 9 b is, for example, a plane parallel to the direction D 1 and the direction D 2 .
- the wiring 9 c includes, for example, a first wiring 9 d provided on the external terminals 3 side and a second wiring 9 f provided on the optical output unit 4 side.
- the first wiring 9 d is disposed between the external terminals and the second wiring 9 f in the direction D 1 .
- the second wiring 9 f is disposed between the first wiring 9 d and the optical output unit 4 in the direction D 1 .
- the first wiring 9 d and the second wiring 9 f are isolated from each other.
- a resistor 16 is mounted on the fourth surface 9 b .
- the resistor 16 is disposed, for example, between the first wiring 9 d and the second wiring 9 f
- the resistor 16 is electrically connected between the first wiring 9 d and the second wiring 9 f
- the inductor 15 is electrically connected between the first wiring 9 d and the second wiring 9 f
- One end (first electrode) of the inductor 15 is connected to the first wiring 9 d
- the other end (second electrode) of the inductor 15 is connected to the second wiring 9 f
- the resistor 16 is connected in parallel with the inductor 15 between the first wiring 9 d and the second wiring 9 f
- the optical semiconductor module 1 includes an RC series circuit 17 .
- the inductor 15 is electrically connected between the RC series circuit 17 and a transmission line 11 described later.
- the inductor 15 functions as, for example, a bias T.
- the bias T supplies a bias (DC potential) to the transmission line 11 .
- the bias becomes a reference potential of a high frequency signal propagating on the transmission line 11 .
- the bias T has a high impedance at the high frequency as viewed from the transmission line 11 , and the influence on the high frequency signal is suppressed to be small.
- the inductor 15 is mounted on the first wiring 9 d and the second wiring 9 f
- the electrode (first electrode) at one end of the inductor 15 is soldered to the first wiring 9 d
- the electrode (second electrode) at the other end of the inductor 15 is soldered to the second wiring 9 f
- the RC series circuit may be configured by forming, for example, the pads 6 for mounting the resistor on the inner surface of the housing 2 and the pads 6 for mounting the capacitor and connecting these pads by wiring.
- the wiring to which these pads connect may be formed by plating or vapor deposition.
- the AlN substrate 8 has the transmission line 11 on the second surface 8 b opposite to the TEC 7 .
- the transmission line 11 includes a ground wiring 11 c running in parallel and a high-frequency wiring 11 b extending in one direction (D 1 direction) while maintaining a constant distance.
- the ground wiring 11 c includes a first ground wiring portion 11 d on which a die 12 , a chip 13 , and a resistor 14 are mounted and a second ground wiring portion 11 f located opposite to the first ground wiring portion 11 d as viewed from the high-frequency wiring 11 b .
- the second ground wiring portion 11 f is located opposite to the first ground wiring portion 11 d as viewed from the high-frequency wiring 11 b .
- the high-frequency wiring 11 b is disposed between the first ground wiring portion 11 d and the second ground wiring portion 11 f in the direction D 2 . It is noted that the first ground wiring portion 11 d and the second ground wiring portion 11 f are connected to each other between the high-frequency wiring 11 b and the optical output unit 4 . Similar to the transmission line 11 , the ground wiring 11 c may not be the wiring extending in one direction but may be a wide wiring pattern having a portion that maintains a certain distance from the transmission line.
- a wire W 1 , a wire W 2 , a wire W 3 , and a wire W 4 extend from the die 12 , the first ground wiring portion 11 d , the high-frequency wiring 11 b , and the second ground wiring portion 11 f , respectively.
- the optical semiconductor module 1 further connects a wire W 5 connecting the die 12 and the laser diode 10 b to each other, a wire W 6 connecting one end of the resistor 14 and the modulator 10 c to each other, and a wire W 7 connecting the high-frequency wiring 11 b and the modulator 10 c to each other.
- the optical semiconductor module 1 includes a wire W 8 connecting the RC series circuit 17 and the inductor 15 to each other and a wire W 9 connecting the inductor 15 and the transmission line 11 to each other.
- the wires W 1 , W 2 , W 3 , W 4 , W 5 , W 6 , W 7 , W 8 , and W 9 are, for example, bonding wires.
- the diameters of the wires W 1 , W 2 , W 3 , W 4 , W 5 , W 6 , W 7 , W 8 , and W 9 are, for example, 18 ⁇ m, 25 ⁇ m, or 50 ⁇ m.
- the diameters of the wires W 1 , W 2 , W 3 , W 4 , W 5 , W 6 , W 7 , W 8 , and W 9 may have the same value or different values from each other. It is noted that the wires W 1 , W 2 , W 3 , W 4 , W 5 , W 6 , W 7 , W 8 , and W 9 may not be bonding wires but may be ribbon wires.
- the ribbon wire has a flat cross section rather than a circular cross section of, for example, a bonding wire. For example, in the ribbon wire, the lateral width of the cross section is twice or more of a thickness of the cross section.
- the wire W 9 corresponds to the first wire connecting the inductor 15 and the transmission line 11 to each other.
- the wire W 7 corresponds to the second wire connecting the semiconductor laser element 10 and the transmission line 11 to each other.
- An inductance of the wire W 9 is larger than an inductance of the wire W 7 .
- the wire W 9 may be longer than the wire W 7 .
- a cross-sectional area (diameter as an example) of the wire W 9 may be smaller than a cross-sectional area of the wire W 7 .
- the block 9 has a transmission line 22 on the fourth surface 9 b .
- the transmission line 22 includes a ground wiring 22 c running in parallel and a high-frequency wiring 22 b extending in one direction at a certain distance.
- the ground wiring 22 c includes, for example, a third ground wiring portion 22 d and a fourth ground wiring portion 22 f located opposite to the third ground wiring portion 22 d as viewed from the high-frequency wiring 22 b .
- the AlN substrate 8 has only the first ground wiring portion 11 d.
- the optical semiconductor module 21 further includes, for example, a wire W 10 connecting the third ground wiring portion 22 d formed on the block 9 and the first ground wiring portion 11 d formed on the AlN substrate 8 to each other.
- a wire W 9 extending from the inductor 15 is connected to the transmission line 22 .
- the wire W 7 connects the high-frequency wiring 22 b and the modulator 10 c to each other. Similar to the optical semiconductor module 1 described above, the inductance of the wire W 9 is larger than the inductance of the wire W 7 .
- the AlN substrate 8 has the transmission line 11 .
- An inductor 15 is mounted on the block 9 .
- the semiconductor laser element 10 is mounted on the AlN substrate 8 .
- the block 9 is made of a low dielectric constant material. Therefore, it is possible to reduce a parasitic capacitance of the wiring 9 c formed on the fourth surface 9 b with respect to a ground potential.
- the inductance of the wire W 9 connecting the inductor 15 and the transmission line 11 to each other is larger than the inductance of the wire W 7 connecting the semiconductor laser element 10 and the transmission line 11 to each other.
- the block 9 has the transmission line 22 , and the inductor 15 is mounted on the block 9 .
- the semiconductor laser element 10 is mounted on the AlN substrate 8 .
- the block 9 is made of a low dielectric constant material, the parasitic capacitance of the wiring 9 c formed on the fourth surface 9 b can be reduced.
- the transmission line 22 is formed on a material having a low dielectric constant as compared with the first embodiment, it is possible to suppress a transmission loss (for example, a dielectric tangent) when transmitting the high frequency signal.
- the parasitic capacitance of the transmission line 22 can be reduced. Therefore, it is possible to implement a much wider band in the frequency characteristics of the transmission line 22 .
- the inductance of the wire W 9 connecting the inductor 15 and the transmission line 22 to each other is larger than the inductance of the wire W 7 connecting the semiconductor laser element 10 and the transmission line 22 to each other. Therefore, even in the state where the inductor 15 exists, the influence on the high frequency signal propagating on the high-frequency wiring 22 b can be suppressed. Then, it is possible to implement a wide band of the optical semiconductor module 21 .
- FIG. 5 is a diagram illustrating an equivalent circuit regarding the bias T of the optical semiconductor module 1 (or the optical semiconductor module 21 ).
- the bias T includes, for example, the wire W 9 , the inductor 15 , the resistor 16 , and the RC series circuit 17 .
- FIG. 6 is an equivalent circuit that is a simplification of the equivalent circuit of FIG. 5 . As illustrated in FIGS.
- the inductance L of the wire W 9 extending from the inductor 15 is large, it is possible to implement a wide band of the frequency characteristics of the transmission line 11 under the condition that there is an inductor 15 .
- the block 9 further has the resistor 16 connected in parallel to the inductor 15 . Therefore, the damping effect of the resistor 16 can reduce the dip associated with the parasitic capacitance.
- the optical semiconductor module 1 (or the optical semiconductor module 21 ) further includes the RC series circuit 17 .
- the inductor 15 is electrically connected between the RC series circuit 17 and the transmission line 11 (or the transmission line 22 ). In this case, the transmission dip can be further reduced.
- the block 9 is disposed adjacent to the AlN substrate 8 on the temperature control surface 7 b of the TEC 7 . Therefore, the block 9 on which the inductor 15 is mounted can be disposed at a position adjacent to the AlN substrate 8 .
- the distance between the block 9 and the AlN substrate 8 can be reduced down to 50 to 150 ⁇ m.
- the inductor 15 can be disposed close to the transmission line 11 formed on the AlN substrate 8 .
- the transmission line 22 may be formed on the fourth surface 9 b of the block 9 . In that case, the inductor 15 can be disposed close to the transmission line 22 .
- the AlN substrate 8 and the block 9 are mounted on the temperature control surface 7 b of the TEC 7 .
- the AlN substrate 8 and the block 9 may be mounted directly on the inner surface of the housing 2 .
- the dielectric constant of the low dielectric constant material of the block 9 is smaller than the dielectric constant of the insulator of the AlN substrate 8 . Therefore, since the dielectric constant of the low dielectric constant material of the block 9 is smaller than the dielectric constant of the insulator of the AlN substrate 8 , the parasitic capacitance can be further reduced. At this time, a thickness of the AlN substrate 8 may be allowed to be substantially equal to a thickness of the block 9 . Accordingly, the parasitic capacitance of the wiring connected to the inductor 15 can be reliably reduced as compared with the case where the inductor 15 is mounted on the AlN substrate 8 .
- the inductance of the wire W 9 may be twice or more of the inductance of the wire W 7 . In this case, it is possible to implement a much wider band.
- An optical semiconductor module according to the example is the above-mentioned optical semiconductor module 1 .
- the optical semiconductor module according to the example includes the resistor 16 disposed in parallel with the inductor 15 , and the RC series circuit 17 .
- FIG. 7 illustrates an equivalent circuit relating to the bias T of the optical semiconductor module according to Reference Example. As illustrated in FIG. 7 , the optical semiconductor module according to Reference Example does not have a configuration corresponding to the resistor 16 and the RC series circuit 17 .
- FIG. 8 illustrates the results of simulating the frequency characteristics (transmission characteristics) of the transmission line 11 in each of the optical semiconductor modules of the above Examples and Reference Examples.
- the horizontal axis represents a frequency of a signal transmitted through the transmission line
- the vertical axis represents a ratio of a signal strength (output signal strength) of a signal output from the transmission line with respect to a signal strength (input signal strength) of a signal input to the transmission line in decibel (dB).
- dB decibel
- the output signal strength is smaller than the input signal strength. That is, when there is a loss in the transmission line, the output signal strength is smaller than the input signal strength, so that the value of the transmission characteristic becomes small.
- a large resonance dip transmission dip
- the resonance dip indicates that the signal strength is greatly lost when the signal is transmitted through the transmission line 11 .
- almost no resonance dip occurs similarly to the case where the bias T is not provided. That is, the loss is significantly suppressed.
- the bias T is necessary to provide the reference potential for the high frequency signal propagating on the transmission line.
- the fact that the equivalent characteristics do not deteriorate when the bias T is provided as compared with the case where the bias T is not provided is an example illustrating that the examples are more useful than Reference Examples.
- FIG. 9 illustrates the result of simulation of the transmission characteristics when the inductance of the wire W 9 is changed in the optical semiconductor module according to Example.
- the inductance of the wire W 9 is 300 pH
- a slight dip and high frequency loss occur.
- the inductance of the wire W 9 is 600 pH or more (600 pH or 1.2 nH)
- almost no dip and high frequency loss occur similarly to the case where the bias T is not provided.
- the optical semiconductor module 1 and the optical semiconductor module 21 including the resistor 16 and the RC series circuit 17 are described.
- the optical semiconductor module may be, for example, an optical semiconductor module which does not include the RC series circuit 17 . At least one of the resistor 16 and the RC series circuit 17 may be omitted.
- the example where the die 12 , the chip 13 , and the resistor 14 are mounted on the transmission line 11 is described.
- the type and number of elements mounted on the transmission line 11 are not limited to the above example and can be changed as appropriate.
- the example where the semiconductor laser element 10 is EML is described.
- the semiconductor laser element may be a semiconductor laser element other than EML.
- the substrate is an AlN substrate 8 and the block 9 is a quartz substrate
- the material of the substrate may be other than AlN.
- the block may be made of alumina, FPC or polyimide. That is, the materials of the substrate and the block are not particularly limited as long as the dielectric constant of the low dielectric constant material of the block 9 is smaller than the dielectric constant of the insulator of the substrate.
Landscapes
- Physics & Mathematics (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- General Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Optics & Photonics (AREA)
- Semiconductor Lasers (AREA)
Abstract
An optical semiconductor module according to the embodiment includes: a board including a transmission line; a block including a low-permittivity material; an inductor mounted on the block, the inductor being connected with the transmission line via a first wire, the first wire having a first inductance; a semiconductor laser device mounted on the board, the semiconductor laser device being connected with the transmission line via a second wire, the second wire having a second inductance smaller than the first inductance; and
a housing configured to accommodate the board, the block, the inductor, and the semiconductor laser device.
Description
- The present disclosure relates to an optical semiconductor module.
- The application is based upon and claims the benefit of priority from Japanese Patent Application No. 2020-186793, filed Nov. 9, 2020, the entire contents of which are incorporated herein by reference.
- Japanese Unexamined Patent Publication No. 2017-107920 discloses a semiconductor module having a laser unit and an optical modulator unit manufactured on a substrate. The semiconductor module includes a semiconductor laser in which a DFB laser and an EA modulator are integrated and a subcarrier having a high-frequency wiring which is a coplanar wiring. The semiconductor laser has a ground electrode on a back surface. A step difference formed with an upper stage and a lower stage is formed on an upper surface of the subcarrier. A lower surface of the subcarrier is flat. The high-frequency wiring has a coplanar line formed on the upper stage of the upper surface of the subcarrier. The coplanar line includes a ground wiring and a signal wiring. The ground electrode is formed in the lower stage of the upper surface of the subcarrier. The semiconductor laser is disposed so that the ground electrode provided on the back surface is in contact with the ground electrode of the subcarrier.
- An optical semiconductor module according to one aspect of the present disclosure includes a board including a transmission line; a block including a low-permittivity material; an inductor mounted on the block, the inductor being connected with the transmission line via a first wire, the first wire having a first inductance; a semiconductor laser device mounted on the board, the semiconductor laser device being connected with the transmission line via a second wire, the second wire having a second inductance smaller than the first inductance; and a housing configured to accommodate the board, the block, the inductor, and the semiconductor laser device.
- An optical semiconductor module according to another aspect of the present disclosure includes a board; a block including a low-permittivity material and a transmission line; an inductor mounted on the block, the inductor being connected with the transmission line via a first wire, the first wire having a first inductance; a semiconductor laser device mounted on the board, the semiconductor laser device being connected with the transmission line via a second wire, the second wire having a second inductance smaller than the first inductance; and a housing configured to accommodate the board, the block, the inductor, and the semiconductor laser device.
-
FIG. 1 is a plan view schematically illustrating an internal structure of an optical semiconductor module according to an embodiment. -
FIG. 2 is a plan view schematically illustrating a substrate on which a semiconductor laser element is mounted and a block on which an inductor is mounted in the optical semiconductor module. -
FIG. 3 is a side view schematically illustrating the inductor mounted on the block. -
FIG. 4 is a plan view schematically illustrating the substrate on which the semiconductor laser element is mounted and the block on which the inductor is mounted in an optical semiconductor module different from that inFIG. 2 . -
FIG. 5 is a diagram illustrating an equivalent circuit of an exemplary optical semiconductor module. -
FIG. 6 is a diagram illustrating an equivalent circuit which is a simplification of the equivalent circuit ofFIG. 5 . -
FIG. 7 is a diagram illustrating an equivalent circuit of an optical semiconductor module according to a reference example. -
FIG. 8 is a graph illustrating an example of a relationship between frequency and transmission characteristics. -
FIG. 9 is a graph illustrating an example of a relationship between frequency and transmission characteristics. -
FIG. 10 is a diagram illustrating an equivalent circuit of an optical semiconductor module according to a modified example. -
FIG. 11 is a side view schematically illustrating a temperature control element, a substrate, and a semiconductor laser element of the optical semiconductor module ofFIG. 2 . - Specific examples of an optical semiconductor module according to an embodiment of the present disclosure will be described with reference to the drawings. The present invention is not limited to these examples, and is indicated by the scope of claims and is intended to include all modifications within the scope equivalent to the scope of claims. In the description of the drawings, the same or corresponding elements are denoted by the same reference numerals, and duplicate description will be omitted as appropriate. The drawings are partially simplified or exaggerated for the ease of understanding, and the dimensional ratios and the like are not limited to those described in the drawings.
-
FIG. 1 is a plan view schematically illustrating an internal structure of anoptical semiconductor module 1 according to a first embodiment. Theoptical semiconductor module 1 includes, for example, arectangular housing 2 andexternal terminals 3 provided at one end of thehousing 2 in a direction D1 which is the longitudinal direction of thehousing 2. Theexternal terminals 3 are aligned at one end of thehousing 2 in the direction D1 along a direction D2 which is the width direction of thehousing 2. The direction D2 is a direction intersecting the direction D1. Theexternal terminals 3 are, for example, a terminal that receives a high-speed electric signal from the outside, a terminal that receives a drive current of a laser diode, a terminal that receives a drive current of a TEC, a monitor terminal for detecting a temperature of the laser diode, a terminal that supplies a ground potential (reference potential), and the like. As signals exchanged with the outside via theexternal terminals 3, there are high-speed signals and low-speed signals. The low speed signal includes a DC signal. Thehousing 2 has aninner wall 2 b that defines an internal space S of thehousing 2. An optical output unit 4 that outputs a light beam L (optical transmission signal) is provided at an end of thehousing 2 opposite to theexternal terminal 3 in the direction D1. - The
optical semiconductor module 1 includes, for example, atransmission line 5, apad 6 which is a DC pad, and a thermo-electric cooler (TEC) 7 which is a temperature control element in the internal space S of thehousing 2.FIG. 2 is a schematic plan view in which an upper structure of theTEC 7 is enlarged.FIG. 11 is a side view schematically illustrating the upper structure of theTEC 7. As illustrated inFIGS. 1 and 2 , theoptical semiconductor module 1 includes theTEC 7, an AlN (Aluminum Nitride) substrate 8 (board) on which asemiconductor laser element 10 is mounted, and ablock 9 on which aninductor 15 is mounted. Thetransmission line 5 and thepads 6 are formed on the inner surface of thehousing 2. Thetransmission line 5 and thepads 6 are connected to theexternal terminals 3 by the wiring penetrating theinner wall 2 b. The wirings connecting each of thetransmission line 5 and thepad 6 to theexternal terminal 3 is formed by, for example, metal plating or thin film deposition. Thetransmission line 5 includes asignal wiring 5 s extending in one direction at a certain distance from aground wiring 5 g running in parallel. - For example, the
AlN substrate 8 is stacked and mounted on theTEC 7 in a direction D3 which is the height direction. The direction D3 is a direction intersecting direction D1 and direction D2. Thehousing 2 accommodates, for example, theTEC 7, theAlN substrate 8, theblock 9, thesemiconductor laser element 10, and theinductor 15 in the internal space S. The TEC 7 has aheat sink surface 7 a and atemperature control surface 7 b. The TEC 7 is mounted on thehousing 2 with theheat sink surface 7 a in contact with thehousing 2. Thetemperature control surface 7 b is located opposite to theheat sink surface 7 a in the direction D3. For example, theheat sink surface 7 a and thetemperature control surface 7 b are planes parallel to the directions D1 and D2. More specifically, for example, theAlN substrate 8 is mounted on thetemperature control surface 7 b in contact with thetemperature control surface 7 b. TheAlN substrate 8 has afirst surface 8 a which is a lower surface and asecond surface 8 b which is an upper surface. Thefirst surface 8 a is in surface contact with thetemperature control surface 7 b. Thesecond surface 8 b is a reverse surface of thefirst surface 8 a. TheAlN substrate 8 has thesecond surface 8 b opposite to theTEC 7. Thesemiconductor laser element 10 is mounted on thesecond surface 8 b. Theblock 9 is juxtaposed with theAlN substrate 8 on theTEC 7. TheTEC 7 performs the temperature controlling of, for example, thesemiconductor laser element 10. For example, when a predetermined current is allowed to flow through theTEC 7, heat is absorbed in thetemperature control surface 7 b, and the heat amount absorbed is exhausted from theheat sink surface 7 a. At this time, thesemiconductor laser element 10 is cooled via theAlN substrate 8. For example, when a current is allowed to flow through theTEC 7 in a direction opposite to the predetermined current, heat is absorbed on theheat sink surface 7 a, and the heat amount absorbed is exhausted from thetemperature control surface 7 b. At this time, thesemiconductor laser element 10 is heated via theAlN substrate 8. Theblock 9 is made of a low dielectric constant material (low-permittivity material). For example, theblock 9 is made of quartz. For example, a relative permittivity of the low dielectric constant material is 3 to 5. TheAlN substrate 8 includes, for example, an insulator. The relative permittivity of the low dielectric constant material of theblock 9 is smaller than the relative permittivity of the insulator of theAlN substrate 8. For example, the relative permittivity of the insulator is 8 to 10. Thesemiconductor laser element 10 is, for example, an Electro-absorption Modulator integrated Laser (EML). For example, thesemiconductor laser element 10 includes alaser diode 10 b and anoptical modulator 10 c (modulator). By maintaining the temperature of thesemiconductor laser element 10 at a predetermined temperature, the optical characteristics and the electrical characteristics of thesemiconductor laser element 10 can be stabilized against changes in the external environmental temperature. For example, the peak wavelength of the optical signal output from thesemiconductor laser element 10 can be maintained within a predetermined range. -
FIG. 3 is a side view schematically illustrating theblock 9 and theinductor 15. As illustrated inFIGS. 2 and 3 , theblock 9 has athird surface 9 a which is a lower surface and afourth surface 9 b which is an upper surface. Thethird surface 9 a is connected to thetemperature control surface 7 b. Thefourth surface 9 b is a surface opposite to thethird surface 9 a. Thefourth surface 9 b faces theinductor 15. Awiring 9 c is formed on thefourth surface 9 b. Theblock 9 is mounted, for example, on thetemperature control surface 7 b of theTEC 7. Thethird surface 9 a of theblock 9 is in contact with, for example, thetemperature control surface 7 b of theTEC 7. TheTEC 7 is mounted on the inner surface of thehousing 2 with theheat sink surface 7 a in contact with the inner surface of thehousing 2. Thefourth surface 9 b is, for example, a plane parallel to the direction D1 and the direction D2. Thewiring 9 c includes, for example, afirst wiring 9 d provided on theexternal terminals 3 side and asecond wiring 9 f provided on the optical output unit 4 side. For example, thefirst wiring 9 d is disposed between the external terminals and thesecond wiring 9 f in the direction D1. For example, thesecond wiring 9 f is disposed between thefirst wiring 9 d and the optical output unit 4 in the direction D1. Thefirst wiring 9 d and thesecond wiring 9 f are isolated from each other. Aresistor 16 is mounted on thefourth surface 9 b. Theresistor 16 is disposed, for example, between thefirst wiring 9 d and thesecond wiring 9 f Theresistor 16 is electrically connected between thefirst wiring 9 d and thesecond wiring 9 f Theinductor 15 is electrically connected between thefirst wiring 9 d and thesecond wiring 9 f One end (first electrode) of theinductor 15 is connected to thefirst wiring 9 d, and the other end (second electrode) of theinductor 15 is connected to thesecond wiring 9 f Theresistor 16 is connected in parallel with theinductor 15 between thefirst wiring 9 d and thesecond wiring 9 f Theoptical semiconductor module 1 includes anRC series circuit 17. Theinductor 15 is electrically connected between theRC series circuit 17 and atransmission line 11 described later. Theinductor 15 functions as, for example, a bias T. The bias T supplies a bias (DC potential) to thetransmission line 11. The bias becomes a reference potential of a high frequency signal propagating on thetransmission line 11. The bias T has a high impedance at the high frequency as viewed from thetransmission line 11, and the influence on the high frequency signal is suppressed to be small. Theinductor 15 is mounted on thefirst wiring 9 d and thesecond wiring 9 f For example, the electrode (first electrode) at one end of theinductor 15 is soldered to thefirst wiring 9 d, and the electrode (second electrode) at the other end of theinductor 15 is soldered to thesecond wiring 9 f The RC series circuit may be configured by forming, for example, thepads 6 for mounting the resistor on the inner surface of thehousing 2 and thepads 6 for mounting the capacitor and connecting these pads by wiring. The wiring to which these pads connect may be formed by plating or vapor deposition. - The
AlN substrate 8 has thetransmission line 11 on thesecond surface 8 b opposite to theTEC 7. Thetransmission line 11 includes aground wiring 11 c running in parallel and a high-frequency wiring 11 b extending in one direction (D1 direction) while maintaining a constant distance. For example, theground wiring 11 c includes a firstground wiring portion 11 d on which adie 12, achip 13, and aresistor 14 are mounted and a secondground wiring portion 11 f located opposite to the firstground wiring portion 11 d as viewed from the high-frequency wiring 11 b. The secondground wiring portion 11 f is located opposite to the firstground wiring portion 11 d as viewed from the high-frequency wiring 11 b. In other words, the high-frequency wiring 11 b is disposed between the firstground wiring portion 11 d and the secondground wiring portion 11 f in the direction D2. It is noted that the firstground wiring portion 11 d and the secondground wiring portion 11 f are connected to each other between the high-frequency wiring 11 b and the optical output unit 4. Similar to thetransmission line 11, theground wiring 11 c may not be the wiring extending in one direction but may be a wide wiring pattern having a portion that maintains a certain distance from the transmission line. - A wire W1, a wire W2, a wire W3, and a wire W4 extend from the
die 12, the firstground wiring portion 11 d, the high-frequency wiring 11 b, and the secondground wiring portion 11 f, respectively. For example, theoptical semiconductor module 1 further connects a wire W5 connecting thedie 12 and thelaser diode 10 b to each other, a wire W6 connecting one end of theresistor 14 and themodulator 10 c to each other, and a wire W7 connecting the high-frequency wiring 11 b and themodulator 10 c to each other. - Further, the
optical semiconductor module 1 includes a wire W8 connecting theRC series circuit 17 and theinductor 15 to each other and a wire W9 connecting theinductor 15 and thetransmission line 11 to each other. The wires W1, W2, W3, W4, W5, W6, W7, W8, and W9 are, for example, bonding wires. The diameters of the wires W1, W2, W3, W4, W5, W6, W7, W8, and W9 are, for example, 18 μm, 25 μm, or 50 μm. The diameters of the wires W1, W2, W3, W4, W5, W6, W7, W8, and W9 may have the same value or different values from each other. It is noted that the wires W1, W2, W3, W4, W5, W6, W7, W8, and W9 may not be bonding wires but may be ribbon wires. The ribbon wire has a flat cross section rather than a circular cross section of, for example, a bonding wire. For example, in the ribbon wire, the lateral width of the cross section is twice or more of a thickness of the cross section. The wire W9 corresponds to the first wire connecting theinductor 15 and thetransmission line 11 to each other. The wire W7 corresponds to the second wire connecting thesemiconductor laser element 10 and thetransmission line 11 to each other. An inductance of the wire W9 is larger than an inductance of the wire W7. For example, the wire W9 may be longer than the wire W7. A cross-sectional area (diameter as an example) of the wire W9 may be smaller than a cross-sectional area of the wire W7. - Next, an
optical semiconductor module 21 according to a second embodiment will be described with reference toFIG. 4 . The partial configuration of theoptical semiconductor module 21 according to the second embodiment is the same as the partial configuration of theoptical semiconductor module 1 described above. Therefore, redundant description of theoptical semiconductor module 1 is denoted by the same reference numerals as those of the elements of theoptical semiconductor module 1 and omitted as appropriate. As illustrated inFIG. 4 , in theoptical semiconductor module 21, theblock 9 has atransmission line 22 on thefourth surface 9 b. Thetransmission line 22 includes aground wiring 22 c running in parallel and a high-frequency wiring 22 b extending in one direction at a certain distance. Theground wiring 22 c includes, for example, a thirdground wiring portion 22 d and a fourthground wiring portion 22 f located opposite to the thirdground wiring portion 22 d as viewed from the high-frequency wiring 22 b. For example, in theoptical semiconductor module 21, theAlN substrate 8 has only the firstground wiring portion 11 d. - The
optical semiconductor module 21 further includes, for example, a wire W10 connecting the thirdground wiring portion 22 d formed on theblock 9 and the firstground wiring portion 11 d formed on theAlN substrate 8 to each other. In theoptical semiconductor module 21, a wire W9 extending from theinductor 15 is connected to thetransmission line 22. The wire W7 connects the high-frequency wiring 22 b and themodulator 10 c to each other. Similar to theoptical semiconductor module 1 described above, the inductance of the wire W9 is larger than the inductance of the wire W7. - Next, the functions and effects obtained from the
optical semiconductor modules optical semiconductor module 1 according to the first embodiment, as illustrated inFIG. 2 , theAlN substrate 8 has thetransmission line 11. Aninductor 15 is mounted on theblock 9. Thesemiconductor laser element 10 is mounted on theAlN substrate 8. Theblock 9 is made of a low dielectric constant material. Therefore, it is possible to reduce a parasitic capacitance of thewiring 9 c formed on thefourth surface 9 b with respect to a ground potential. The inductance of the wire W9 connecting theinductor 15 and thetransmission line 11 to each other is larger than the inductance of the wire W7 connecting thesemiconductor laser element 10 and thetransmission line 11 to each other. Since the inductance of the wire W9 connecting theinductor 15 and thetransmission line 11 to each other is large, it is possible to suppress the influence on the high frequency signal propagating on the high-frequency wiring 11 b even in the state where there is aninductor 15. Then, it is possible to implement a wide band of the frequency characteristics of theoptical semiconductor module 1. - In the
optical semiconductor module 21 according to the second embodiment, as illustrated inFIG. 4 , theblock 9 has thetransmission line 22, and theinductor 15 is mounted on theblock 9. Thesemiconductor laser element 10 is mounted on theAlN substrate 8. In theoptical semiconductor module 21, similar to theoptical semiconductor module 1, since theblock 9 is made of a low dielectric constant material, the parasitic capacitance of thewiring 9 c formed on thefourth surface 9 b can be reduced. Since thetransmission line 22 is formed on a material having a low dielectric constant as compared with the first embodiment, it is possible to suppress a transmission loss (for example, a dielectric tangent) when transmitting the high frequency signal. Further, similarly to thewiring 9 c, the parasitic capacitance of thetransmission line 22 can be reduced. Therefore, it is possible to implement a much wider band in the frequency characteristics of thetransmission line 22. The inductance of the wire W9 connecting theinductor 15 and thetransmission line 22 to each other is larger than the inductance of the wire W7 connecting thesemiconductor laser element 10 and thetransmission line 22 to each other. Therefore, even in the state where theinductor 15 exists, the influence on the high frequency signal propagating on the high-frequency wiring 22 b can be suppressed. Then, it is possible to implement a wide band of theoptical semiconductor module 21. -
FIG. 5 is a diagram illustrating an equivalent circuit regarding the bias T of the optical semiconductor module 1 (or the optical semiconductor module 21). The bias T includes, for example, the wire W9, theinductor 15, theresistor 16, and theRC series circuit 17.FIG. 6 is an equivalent circuit that is a simplification of the equivalent circuit ofFIG. 5 . As illustrated inFIGS. 5 and 6 , when the inductance of the wire W9 is denoted by L, the resistance of theresistor 16 is denoted by Rpara, the resistance of theRC series circuit 17 is denoted by Rdump, and R=Rpara+Rdump, then a resonance frequency ω0 of a series circuit of the inductance L and the RC parallel circuit is expressed by Mathematical -
- In Mathematical Formula (1), if R→∞, ω0 is equal to a resonance frequency in a series LC resonance circuit of the inductance L and the capacitance C. On the other hand, the impedance Z (ω=ω0) at the resonance frequency ω0 is expressed by Mathematical Formula (2).
-
- In the optical semiconductor module 1 (or the optical semiconductor module 21), since R is not 0, the impedance Z (ω=ω0) does not become 0, and the smaller the ω0 (the larger L), the higher the impedance Z. Therefore, under the condition that the value of the product CR of the capacitance C and the resistor R in Mathematical Formulas (1) and (2) is constant, as the value of L is larger, the decrease in impedance at the resonance frequency can be suppressed. As described above, when the inductance L of the wire W9 extending from the
inductor 15 is large, it is possible to implement a wide band of the frequency characteristics of thetransmission line 11 under the condition that there is aninductor 15. - In this embodiment, the
block 9 further has theresistor 16 connected in parallel to theinductor 15. Therefore, the damping effect of theresistor 16 can reduce the dip associated with the parasitic capacitance. - In the present embodiment, the optical semiconductor module 1 (or the optical semiconductor module 21) further includes the
RC series circuit 17. Theinductor 15 is electrically connected between theRC series circuit 17 and the transmission line 11 (or the transmission line 22). In this case, the transmission dip can be further reduced. - In this embodiment, the
block 9 is disposed adjacent to theAlN substrate 8 on thetemperature control surface 7 b of theTEC 7. Therefore, theblock 9 on which theinductor 15 is mounted can be disposed at a position adjacent to theAlN substrate 8. For example, in a plan view from the direction D3, the distance between theblock 9 and theAlN substrate 8 can be reduced down to 50 to 150 μm. As a result, theinductor 15 can be disposed close to thetransmission line 11 formed on theAlN substrate 8. Thetransmission line 22 may be formed on thefourth surface 9 b of theblock 9. In that case, theinductor 15 can be disposed close to thetransmission line 22. It is noted that, for example, theAlN substrate 8 and theblock 9 are mounted on thetemperature control surface 7 b of theTEC 7. However, when thesemiconductor laser element 10 does not require temperature control, theAlN substrate 8 and theblock 9 may be mounted directly on the inner surface of thehousing 2. - In the present embodiment, the dielectric constant of the low dielectric constant material of the
block 9 is smaller than the dielectric constant of the insulator of theAlN substrate 8. Therefore, since the dielectric constant of the low dielectric constant material of theblock 9 is smaller than the dielectric constant of the insulator of theAlN substrate 8, the parasitic capacitance can be further reduced. At this time, a thickness of theAlN substrate 8 may be allowed to be substantially equal to a thickness of theblock 9. Accordingly, the parasitic capacitance of the wiring connected to theinductor 15 can be reliably reduced as compared with the case where theinductor 15 is mounted on theAlN substrate 8. - In the present embodiment, the inductance of the wire W9 may be twice or more of the inductance of the wire W7. In this case, it is possible to implement a much wider band.
- Next, an example will be described. The present invention is not limited to the following example. An optical semiconductor module according to the example is the above-mentioned
optical semiconductor module 1. As illustrated inFIG. 5 , the optical semiconductor module according to the example includes theresistor 16 disposed in parallel with theinductor 15, and theRC series circuit 17.FIG. 7 illustrates an equivalent circuit relating to the bias T of the optical semiconductor module according to Reference Example. As illustrated inFIG. 7 , the optical semiconductor module according to Reference Example does not have a configuration corresponding to theresistor 16 and theRC series circuit 17. -
FIG. 8 illustrates the results of simulating the frequency characteristics (transmission characteristics) of thetransmission line 11 in each of the optical semiconductor modules of the above Examples and Reference Examples. InFIG. 8 , the horizontal axis represents a frequency of a signal transmitted through the transmission line, and the vertical axis represents a ratio of a signal strength (output signal strength) of a signal output from the transmission line with respect to a signal strength (input signal strength) of a signal input to the transmission line in decibel (dB). For example, when the output signal strength is equal to the input signal strength, the output signal strength becomes 0 dB. When the value of the transmission characteristic is larger than 0 dB, the output signal strength is larger than the input signal strength. When the value of the transmission characteristic is smaller than 0 dB, the output signal strength is smaller than the input signal strength. That is, when there is a loss in the transmission line, the output signal strength is smaller than the input signal strength, so that the value of the transmission characteristic becomes small. As illustrated inFIG. 8 , in the optical semiconductor module according to Reference Example which does not have theresistor 16 and theRC series circuit 17, a large resonance dip (transmission dip) occurs at a frequency of around 30 GHz. The resonance dip indicates that the signal strength is greatly lost when the signal is transmitted through thetransmission line 11. In contrast, it is found that, in the optical semiconductor module according to the embodiment, almost no resonance dip occurs similarly to the case where the bias T is not provided. That is, the loss is significantly suppressed. The bias T is necessary to provide the reference potential for the high frequency signal propagating on the transmission line. The fact that the equivalent characteristics do not deteriorate when the bias T is provided as compared with the case where the bias T is not provided is an example illustrating that the examples are more useful than Reference Examples. -
FIG. 9 illustrates the result of simulation of the transmission characteristics when the inductance of the wire W9 is changed in the optical semiconductor module according to Example. As illustrated inFIG. 9 , when the inductance of the wire W9 is 300 pH, a slight dip and high frequency loss occur. In contrast, it is found that, when the inductance of the wire W9 is 600 pH or more (600 pH or 1.2 nH), almost no dip and high frequency loss occur similarly to the case where the bias T is not provided. - The embodiments and examples of the optical semiconductor module according to the present disclosure have been described above. However, the present invention is not limited to the above-described embodiments or examples. It is easily recognized by those skilled in the art that the present invention can be changed and modified in various forms within the scope of the spirit described in the claims.
- For example, in the above-described embodiment, as illustrated in
FIG. 5 , theoptical semiconductor module 1 and theoptical semiconductor module 21 including theresistor 16 and theRC series circuit 17 are described. However, as illustrated inFIG. 10 , the optical semiconductor module may be, for example, an optical semiconductor module which does not include theRC series circuit 17. At least one of theresistor 16 and theRC series circuit 17 may be omitted. - In the above-described embodiment, the example where the
die 12, thechip 13, and theresistor 14 are mounted on thetransmission line 11 is described. However, the type and number of elements mounted on thetransmission line 11 are not limited to the above example and can be changed as appropriate. In the above-described embodiment, the example where thesemiconductor laser element 10 is EML is described. However, the semiconductor laser element may be a semiconductor laser element other than EML. - In the above-described embodiment, the example where the substrate is an
AlN substrate 8 and theblock 9 is a quartz substrate is described. However, the material of the substrate may be other than AlN. The block may be made of alumina, FPC or polyimide. That is, the materials of the substrate and the block are not particularly limited as long as the dielectric constant of the low dielectric constant material of theblock 9 is smaller than the dielectric constant of the insulator of the substrate.
Claims (12)
1. An optical semiconductor module comprising:
a board including a transmission line;
a block including a low-permittivity material;
an inductor mounted on the block, the inductor being connected with the transmission line via a first wire, the first wire having a first inductance;
a semiconductor laser device mounted on the board, the semiconductor laser device being connected with the transmission line via a second wire, the second wire having a second inductance smaller than the first inductance; and
a housing configured to accommodate the board, the block, the inductor, and the semiconductor laser device.
2. An optical semiconductor module comprising:
a board;
a block including a low-permittivity material and a transmission line;
an inductor mounted on the block, the inductor being connected with the transmission line via a first wire, the first wire having a first inductance;
a semiconductor laser device mounted on the board, the semiconductor laser device being connected with the transmission line via a second wire, the second wire having a second inductance smaller than the first inductance; and
a housing configured to accommodate the board, the block, the inductor, and the semiconductor laser device.
3. The optical semiconductor module according to claim 1 , wherein the block further has a resistor connected in parallel with the inductor.
4. The optical semiconductor module according to claim 1 , further comprising an RC series circuit,
wherein the inductor is connected between the RC series circuit and the transmission line.
5. The optical semiconductor module according to claim 1 , wherein the block is disposed adjacent to the board inside the housing.
6. The optical semiconductor module according to claim 1 , wherein a dielectric constant of the low-permittivity material is smaller than a dielectric constant of an insulator of the board.
7. The optical semiconductor module according to claim 1 , wherein the inductance of the first wire is twice or more of the inductance of the second wire.
8. The optical semiconductor module according to claim 2 , wherein the block further has a resistor connected in parallel with the inductor.
9. The optical semiconductor module according to claim 2 , further comprising an RC series circuit,
wherein the inductor is connected between the RC series circuit and the transmission line.
10. The optical semiconductor module according to claim 2 , wherein the block is disposed adjacent to the board inside the housing.
11. The optical semiconductor module according to claim 2 , wherein a dielectric constant of the low-permittivity material is smaller than a dielectric constant of an insulator of the board.
12. The optical semiconductor module according to claim 2 , wherein the inductance of the first wire is twice or more of the inductance of the second wire.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2020-186793 | 2020-11-09 | ||
JP2020186793A JP2022076389A (en) | 2020-11-09 | 2020-11-09 | Optical semiconductor module |
Publications (1)
Publication Number | Publication Date |
---|---|
US20220149592A1 true US20220149592A1 (en) | 2022-05-12 |
Family
ID=81453649
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US17/521,660 Pending US20220149592A1 (en) | 2020-11-09 | 2021-11-08 | Optical semiconductor module |
Country Status (3)
Country | Link |
---|---|
US (1) | US20220149592A1 (en) |
JP (1) | JP2022076389A (en) |
CN (1) | CN114530756A (en) |
-
2020
- 2020-11-09 JP JP2020186793A patent/JP2022076389A/en active Pending
-
2021
- 2021-11-04 CN CN202111298377.6A patent/CN114530756A/en active Pending
- 2021-11-08 US US17/521,660 patent/US20220149592A1/en active Pending
Also Published As
Publication number | Publication date |
---|---|
JP2022076389A (en) | 2022-05-19 |
CN114530756A (en) | 2022-05-24 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US10411432B2 (en) | Optical transmitter providing coplanar line on carrier | |
US7869479B2 (en) | Optical module | |
US9980379B2 (en) | Optical module | |
EP1655630B1 (en) | Optical module | |
US11206087B2 (en) | Optical module and optical transmitter | |
JP5144628B2 (en) | TO-CAN type TOSA module | |
US20090029570A1 (en) | Relay substrate and substrate assembly | |
JP3553222B2 (en) | Optical modulator module | |
US11340412B2 (en) | Optical module | |
US6823145B1 (en) | Optical transmitter module | |
US11641240B2 (en) | Optical module | |
US7605402B2 (en) | Structure of chip carrier for semiconductor optical device, optical module, and optical transmitter and receiver | |
US11503715B2 (en) | Optical module | |
US20190182949A1 (en) | Flexible printed circuit board and optical module | |
JP7468846B2 (en) | Optical semiconductor device and carrier | |
JP2004093606A (en) | Optical module and optical transmitter | |
US20220149592A1 (en) | Optical semiconductor module | |
US5926308A (en) | High-speed optical modulator module | |
US6642808B2 (en) | High frequency package, wiring board, and high frequency module having a cyclically varying transmission characteristic | |
US7196909B2 (en) | AC coupling circuit having a large capacitance and a good frequency response | |
US6856442B2 (en) | Transmission line, optical module using the same and manufacturing method of optical module | |
JP2000164970A (en) | Optical element module | |
US11909170B2 (en) | Semiconductor light emitting device and optical subassembly | |
US11744008B2 (en) | Printed board and printed board assembly | |
JP6754334B2 (en) | Termination circuit and wiring board that composes the termination circuit |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: SUMITOMO ELECTRIC INDUSTRIES, LTD., JAPAN Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:ITABASHI, NAOKI;REEL/FRAME:058054/0699 Effective date: 20211101 |
|
STPP | Information on status: patent application and granting procedure in general |
Free format text: DOCKETED NEW CASE - READY FOR EXAMINATION |